c++

#include <bits/stdc++.h>
using namespace std;
long long int n,i,j,k=0,maxn=0,s=0;
struct ss{
	long long int a,b;
}E[250010];
bool cmp(ss x,ss y)
{
    return x.b<y.b;
}
int main ()
{
	cin>>n;
	for(i=1;i<=n;i++){
		cin>>E[i].a>>E[i].b;
		if(E[i].b>maxn){
			maxn=E[i].b;
		}
	}
	sort(E+1,E+1+n,cmp);
	for(i=1;i<=n;i++){
		if(s+E[i].a<=E[i].b&&E[i].a<=E[i].b){
			s=s+E[i].a;
			k++;
		}
	}
	cout<<k<<"\n";
	return 0;
}

谁来帮帮我？